Exhaust gases of an automobile engine are released to the atmosphere through an exhaust pipe, and this exhaust pipe is subjected to repeated stress owing to such as the roll behavior and vibration of the engine, with the result that there is a possibility of causing a fatigue failure of the exhaust pipe, and there are also cases where the engine vibration causes the exhaust pipe to resonate, thereby deteriorating the quietness of the compartment interior. To overcome such problems, a means has been adopted to absorb the stress by disposing a spherical pipe joint at a predetermined portion of the exhaust pipe.
In Patent Document 1, for example, a spherical annular seal member is proposed which has a cylindrical inner surface defining a through hole in a central portion thereof, an outer surface formed in the shape of a partially convex spherical surface, and annular end faces on large- and small-diameter sides of the outer surface. In its inner portion extending from the cylindrical inner surface to the outer surface formed in the shape of the partially convex spherical surface, the spherical annular seal member has a reinforcing member made from a compressed metal wire net sheet, as well as a heat-resistant material which contains expanded graphite, fills meshes of the metal wire net sheet of this reinforcing member, and is compressed in such a manner as to be formed integrally with the metal wire net sheet of the reinforcing member in mixed form.